Dutch red-backed shrikes in winter are widely scattered across southern Africa, according to new data collected using geolocators. Their migration flyways may also be far apart. Shrikes populations thus have a high degree of spreading risks during migration and wintering.

Researchers of the Bargerveen Foundation in the ‘Year of the shrikes’ 2012 have provided twenty Drenthe province red-backed shrikes with geolocators. Six of these shrikes were found again in 2013, three of which could be caught again. This is necessary to read geolocators, which, like mini computers, are carried like backpacks. In 2014, the researchers hope to get back some geolocators again.

Southern Africa

The data from the first three shrikes are now analyzed by a specialist, Raymond Klaassen. All three birds followed a route with stops in the autumn in the Sahel (yellow in the figure), and in the spring in the Horn of Africa (light blue). The variation in migratory paths and the final wintering areas (red) is large. One of the shrikes appeared to fly through Chad and the Central African Republic to Northern Namibia. A second bird narrowly dodged the hunter’s nets on the Egyptian coast and flew after a few weeks of rest in South Sudan to Botswana. The third bird’s migration route is still difficult to analyze, but it is certain that it wintered in Mozambique.

Differences in migrating and hibernating mean there is a low risk that birds from the same population will experience similar problems. The main problems are likely to be hunting, especially around the Mediterranean, and adverse weather conditions. Only during their joint spring stop-over in the Horn of Africa red-backed shrikes face the same problems. That was proved in 2011 when all European red-backed shrikes arrived weeks later than normally at their breeding grounds after a prolonged drought in Ethiopia. Together with the Danish researchers who discovered that, the Bargerveen Foundation will investigate further the influence of factors during migration and wintering of the Dutch population.